Structural, DSC, and IR Studies on a New Organic-Cation Cyclohexaphosphate: [NH 3-(CH 2) 2-NH 2-(CH 2) 2-NH 3] 2P 6O 18 · 2H 2O

Abstract

Chemical preparation, calorimetric studies, crystal structure, and IR absorption spectra are given for a new organic cyclohexaphosphate. The aza-3 pentanediyl-1,5 dihydrate, [NH 3-(CH 2) 2-NH 2-(CH 2) 2-NH 3] 2P 6O 18 · 2H 2O is triclinic P1̄ with unit cell dimensions, a = 8.709(2), b = 9.729(2), c = 9.145(2) Å, α = 99.11(2)°, β = 110.70(2)°, γ = 67.19(2)°, and Z = 1, V = 667.9(6) Å 3, ρ m = 1.72 g · cm -3, μ = 0.268 mm -1. The refinement of data, collected at room temperature, leads to a final R = 0.035 for 3844 independent reflections. The P 6O 18 ring anion is centrosymmetric and significantly distorted with P-P-P angles varying from 93.6° to 134.8° as commonly observed for such rings with 1̄ internal symmetry. A three-dimensional network of strong hydrogen bonds interconnects the structural arrangement. Of the eight hydrogen atoms in the organic group, seven are connected to the external oxygen atoms of four phosphoric rings and form a complex union of formula [C 4N 3H 16(P 6O 18) 4] -21; the remaining one establishes a hydrogen bond with a water molecule which links, with the help of its proper hydrogen atoms, successive complex anions. The hydrogen bonding geometries are discussed.